Drilling fluid, apparatus, and method

ABSTRACT

Disclosed are drilling fluids suitable for use in connection with oil well drilling. The drilling fluids of the invention include in one embodiment a liquid base, an alkyl glucoside, such as methyl glucoside, and a borehole stability agent that includes a maltodextrin, a carboxyalkyl starch, a hemicellulose-containing material, or a mixture of the foregoing. In another embodiment, the drilling fluid includes a liquid base and desugared molasses solids, preferably in combination with an alkyl glucoside and more preferably in further combination with one of the aforementioned borehole stability agents. The drilling fluids of the invention surprisingly have a reduced tendency to swell shale as compared with known drilling fluids. Also disclosed are a drilling apparatus and process. The drilling apparatus includes a drill string, which may be conventional, that is fluidically coupled to a source of drilling fluid, the source of drilling fluid including the drilling fluid of the invention. The process of the invention includes the step of circulating the drilling fluid of the invention through a drill string during borehole drilling.

RELATED APPLICATION

[0001] This application is a continuation-in-part of prior applicationSer. No. 5 09/638,564 (Schilling et al.), the entire contents of whichare hereby incorporated by reference in their entireties.

TECHNICAL FIELD OF THE INVENTION

[0002] The invention is in the area of drilling fluids used inconnection with drilling wells, such as oil wells and water wells. Theinvention is also directed towards a drilling apparatus and process.

BACKGROUND OF THE INVENTION

[0003] In drilling a well or other similar borehole, a drill bit isoperatively coupled, usually by a drill string, to a drive which rotatesthe drill bit to cause the drill bit to bore into the earth. A drillingfluid, or drilling mud, is circulated through the borehole annulus. Thedrilling fluid passes through the drilling string and to the surfacethrough the drill bit for cooling and lubricating the drill bit and forcarrying rock cuttings generated by the cutting action of the bit to thesurface. The drilling fluid may be a gas, but more typically is aliquid.

[0004] Many liquids suitable for use as drilling fluids are known. Somedrilling fluids are oil-based. Such oil-based fluids suffer from anumber of drawbacks, particularly, their adverse effects on theenvironment. Oil-based fluids also can be costly to purchase and todispose of.

[0005] Other drilling fluids are water-based or constitute an emulsionof oil in water or water in oil. Such fluids often are inexpensivecompared to oil-based fluids, and are less costly to dispose of.Water-based fluids also pose less of a risk to the environment than dooil-based fluids. One drawback associated with water-based fluids isthat the water in the fluid tends to promote borehole instability,particularly when shale is encountered in the drilling process. Thewater-based fluid may adsorb and absorb into pores in the shale, thuscausing the shale to swell and thereby tending to cause the borehole tocollapse.

[0006] In recognition of this drawback, water-based drilling fluids haveincorporated an alkyl glycoside, such as methyl glucoside, into thedrilling fluid. It is known that methyl glucoside serves as a boreholestabilizing agent that functions by inhibiting shale swelling. Themechanism of action of methyl glucoside is not fully understood, but isbelieved to be associated with gel formation or an ion exchangephenomenon. It is generally believed that the methyl glucoside, inadding gel strength to the drilling fluid, causes more rapid formationof filter cake on the borehole wall thereby allowing less water filtrateto reach the surrounding shales. This is believed to reduce swelling andsloughing of the shale.

[0007] While known drilling fluids that include methyl glucoside aresatisfactory, there remains room for improvement in such fluids in thearea of borehole stability. It is a general object of the invention toprovide a drilling fluid that is suitable for use in borehole drilling.Another general object is to provide a drilling apparatus and processthat incorporate the drilling fluid of the invention.

THE INVENTION

[0008] It has now been discovered that both maltodextrins, on the onehand, and hemicellulose-containing materials, on the other hand,function to assist glycosides in promoting borehole stability in adrilling fluid. It has further been found that carboxyalkyl starches, inparticular carboxymethyl starches, also function to assist glycosides inpromoting borehole stability. Surprisingly, these ingredients promoteborehole stability more so than other organic species of similar originor chemical structure when used in conjunction with an alkyl glucoside.In accordance with the invention, a drilling fluid comprises a liquidbase, an alkyl glycoside, which preferably is methyl glucoside; and aborehole stability agent that comprises a maltodextrin, a carboxyalkylstarch, and/or hemicellulose. Also encompassed by the invention is adrilling fluid that includes methyl glucoside and cellulose. Theinvention also encompasses a drilling apparatus and a process fordrilling. The drilling apparatus comprises a drilling string that isfluidically coupled to a source of drilling fluid, the drilling fluidincluding in one embodiment a liquid base, an alkyl glycoside, and oneor more of a maltodextrin, a carboxyalkyl starch, and ahemicellulose-containing material and, in another embodiment, a liquidbase, an alkyl glycoside, and cellulose. The process of the inventionincludes the steps of circulating the drilling fluid of the inventionthrough a drill string as a borehole is cut into the earth, optionallyin conjunction with hemicellulose, a maltodextrin, a carboxyalkyl starchand/or cellulose.

[0009] It has further been found that desugared molasses functionseffectively as a borehole stabilizing agent. In accordance with anotherembodiment of the invention, a drilling fluid comprises a liquid base,optionally an alkyl glucoside, and a borehole stabilizing agent thatcomprises desugared molasses solids. Also encompassed by this embodimentof the invention are a drilling apparatus and a process for drilling.More generally, the various borehole stabilizing agents discussedhereinabove may be combined with the alkyl glucoside to form a drillingfluid. Thus, for instance, the drilling fluid may comprise an alkylglucoside, desugared molasses solids, and one or more of hemicellulose,a maltodextrin, and a carboxyalkyl starch.

[0010] Other features and embodiments of the invention are discussedhereinbelow and are set forth in the pending claims.

BRIEF DESCRIPTION OF THE DRAWING

[0011] The Figure is a schematic representation of an oil well drillingapparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The drilling fluid of the invention generally comprises in oneembodiment a liquid base, an alkyl glycoside, and a borehole stabilityagent, and may include other components and additives as may be deemedappropriate. In another embodiment, the drilling fluid comprises aliquid base, desugared molasses solids, optionally in conjunction withan alkyl glucoside or a borehole stability agent, and further optionally

[0013] including other components and additives as may be deemedappropriate. The liquid base used in the drilling fluid of the inventioncomprises water, a water-miscible liquid, or a mixture of awater-miscible liquid with water. If the liquid base includes water, thewater may be provided from any suitable source. For example, when theoil drilling apparatus is off-shore or near the ocean, sea water is thepreferred liquid base inasmuch as it is freely available. The water mayalso comprise treated water, softened water, tap water, natural orartificial brine, or other suitable water source. The water miscibleliquid may be glycerine, polyglycerine, a polyether, a polyol, or othersuitable water miscible liquid. The liquid base may be present in anyamount suitable to carry, dissolve and/or suspend the components of thedrilling fluid. Preferably, the liquid base is present in the drillingfluid in a total amount ranging from about 5 to about 7.5, morepreferably, about 5.5 to about 6 lbs./gallon. It is further contemplatedthat the liquid base may be used in an oil-based system that comprisesan emulsion of oil in water or water in oil. The drilling fluid of theinvention in one embodiment further includes an alkyl glycoside. Alkylglycosides are a known class of industrial chemicals and are formed bythe substitution of the hemiacetal hydroxyl group of a lower ordersaccharide (i.e., a polysaccharide having a degree of polymerizationless than about 7) with an alkyl radical having from one to four carbonatoms. The alkyl radical may be methyl, ethyl, propyl, isopropyl,n-butyl, s-butyl or t-butyl, and the saccharide may be, for example,glucose, maltose, maltotriose, or maltotetraose.

[0014] The alkyl glycoside used in conjunction with the invention ispreferably methyl glucoside. Most preferably, the methyl glucoside isprovided in the form of MeG-206, an aqueous methyl glucoside solutionsold by Grain Processing Corporation of Muscatine, Iowa. MeG-206 is a60% aqueous solution of methyl glucoside, the methyl glucoside beingpresent in a 2:1 ratio of α:β isomers (this ratio should be regarded asapproximate). The methyl glucoside also may be provided in the form ofMeG-365, also sold by Grain Processing Corporation of Muscatine, Iowa.MeG-365 is a 65% aqueous solution of methyl glucoside which exists inthe solution as a 2:1 ratio of α:β isomers (this ratio also should beregarded as approximate). Another suitable methyl glucoside may beprovided as a 70% 1:1 (approximate) mixture of α:β methyl glucosideisomers. More generally, any other suitable mixture of methyl glucosideisomers may be employed in conjunction with the invention.

[0015] The alkyl glycoside may be present in any amount effective toinhibit shale swelling. Preferably, when the alkyl glycoside is methylglucoside, the methyl glucoside is present in the drilling fluid in anamount ranging from about 2 to about 4 lbs./gallon of the drilling fluid(dry basis MeG).

[0016] In another embodiment of the invention, the drilling fluidcomprises or includes desugared molasses solids. It is contemplated thatnon-desugared molasses may be substituted for molasses in thisembodiment. Desugared molasses is the by-product of the process used toextract sugar from sugar beet or cane sugar molasses or from other typesof molasses (e.g., sorghum or citrus molasses). Preferred embodiments ofthe invention make use of desugared sugar beet molasses or desugaredsugar cane molasses. With respect to sugar beet molasses, as is wellknown in the art, sugar beets are used to produce commercial grade sugarthat serves as a substitute for the often more expensive cane sugar. Theolder of the two most widely used processes of removing sugar from sugarbeets involves cleaning the beets and slicing them into thin chips. Thesliced beets are then subjected to a sugar extraction process wherebyhot water is passed over the beets for approximately one hour. Thisprocess removes most, but not all, of the sugar from the beets in theform of beet “juice.” The beets are then pressed in screw presses toremove the remaining juice therefrom. The juice is then subjected to aprocess called carbonation, whereby small clumps of chalk are providedin the juice to filter out any non-sugars. The chalk is then filteredfrom the juice, which is then evaporated a syrup. The syrup is thenboiled until sugar crystals form therein. Once the crystals form, theresulting mixture is centrifuged to separate the crystals from theremaining product, which remaining product is characterized as molasses.Desugared sugar beet molasses preferably is prepared by a process knownas the Steffen process, in which a calcium precipitate is formed toremove additional sugar. This process is described briefly in U.S. Pat.No. 5,639,319 to Daly, which purports to teach the use of desugaredsugar beet molasses as a tire ballast. Another process for desugaringmolasses involves an ion exchange reduction of the sugar content. Withrespect to desugared sugar cane molasses, this product may be obtainedvia any method or process known in the art or otherwise found to besuitable. Likewise, sugar beet or other types of molasses may beobtained via any other method known in the art or found to be suitable.

[0017] In either instance, the desugared sugar molasses is a liquid thatcontains approximately 60 to 80% solids, often 60 to 75% solids. Thesolids contained in the sugar beet molasses are not particularly wellcharacterized, but generally speaking, the molasses generally includesresiduals, organic acids, salts, proteinaceous material, and othermaterials. In some embodiments of the invention, desugared molasses isused alone as the drilling fluid in a drilling process or apparatus. Forthis embodiment, the molasses can be said to comprise a liquid base(water) in which is carried desugared molasses solids. It should benoted that although the invention encompasses embodiments whereinmolasses solids are obtained via drying a molasses solution to solids,the invention is not limited thereto, and the “liquid base” and“desugared molasses solids” may together comprise conventional desugaredmolasses or conventional desugared molasses that has been diluted. Morepreferably, the desugared sugar beet molasses is diluted with a liquidbase such as water to a solids content of about 20% to about 60%. Inaccordance with a highly preferred embodiment of the invention, thedrilling fluid includes both an alkyl glucoside and desugared molassessolids. In this embodiment, the alkyl glucoside and the desugared sugarbeet molasses solids may be present in any proportion with respect toeach other and preferably are present in a total solids content in thedrilling fluid ranging from about 40% to about 80%.

[0018] In accordance with preferred embodiments of the invention, thedrilling fluid further includes a borehole stability agent that isselected from among maltodextrins, carboxymethyl starches, andhemicellulose. With respect to hemicellulose, hemicellulose is a termused to refer to a wide variety of heteropolysaccharides found inassociation with cellulose in plant species. The hemicellulose functionsto inhibit shale swelling, and may further function as a fluid losscontrol agent. The hemicellulose may be added in a purified form. Mostpreferably, the hemicellulose-containing material is produced inaccordance with the teachings of U.S. Pat. No. 4,038,481 (Antrim etal.), which discloses the alkaline hydrolysis of corn hulls to yieldplural phases including a hemicellulose-rich fraction. Thehemicellulose-rich fraction prepared in accordance with the teachings ofthis patent may be used as the hemicellulose-containing material withoutsubsequent isolation or purification, or this fraction may beconcentrated or otherwise modified. The alkaline hydrolysis itselfpreferably is conducted using potassium hydroxide as the alkalinehydrolyzing species. Potassium is itself believed to function as a shalestability enhancer in a drilling fluid, and thus the potassium hydroxidedigest of corn hulls is believed to be particularly suitable for use inconjunction with the invention. More economically, an unrefined aqueousslurry (for example, an alkaline digest of corn hulls) may be used. Moregenerally, hemicellulose may be provided in an unpurified, somewhat“crude” form or in a highly purified form with the purer hemicellulosebeing preferred from a technical standpoint, but with cruder forms beingmore economical. In some instances a greater amount of the crudehemicellulose may be desired to achieve the same results as by adding apurer form of hemicellulose.

[0019] The hemicellulose-containing material is used to providehemicellulose in the drilling fluid in an amount effective to inhibitswelling of shale. Preferably, if the drilling fluid does not include amaltodextrin, the hemicellulose is present in an amount ranging fromabout 0.002 to about 0.2 lbs./gallon by dry basis weight. In thisembodiment of the invention, these amounts are irrespective of theamount of any cellulose in the drilling fluid.

[0020] The drilling fluid may also include a maltodextrin in lieu of orin addition to the hemicellulose-containing material. Maltodextrins areoligo- or poly-saccharides in which the saccharides are linkedexclusively or predominantly by 1-4 linkages. In preferred embodiments,at least 50 percent of the saccharide units in the maltodextrin arelinked via 1-4 linkages. More preferably, at least about 60 percent ofthe saccharide units are linked via 1-4 linkages; even more preferably,at least about 80 percent of the saccharide units are so linked. Whilethe drilling fluid may incorporate any maltodextrin or mixture ofmaltodextrin species, the invention is particularly applicable tomixtures of maltodextrin species in which at least a portion of themaltodextrins in the mixture have a degree of polymerization (DP)greater than 5.

[0021] Preferably, at least one of the maltodextrin species in themixture has a DP of 8 or more. More preferably, at least one species hasa DP of at least 10. For example, in some embodiments of the invention,a maltodextrin mixture in which at least 80 percent of the maltodextrinspecies in the mixture have a DP greater than 5 is used, and in somesuch embodiments, preferably at least 60 percent have a DP greater than8. In another embodiment, a maltodextrin in which at least 80 percent ofthe maltodextrin species have a DP greater than 10 is used. In someembodiments of the invention, the DP profile of the maltodextrin is suchthat at least 75 percent of the maltodextrin species in the mixture havea DP greater than 5 and at least 40 percent of the species in themixture have a DP greater than 10. The maltodextrins may includesaccharide species having an odd DP value, and the profile may bepartially defined by a saccharide species having a DP value of 1, forexample, dextrose or sorbitol. The mixture further may include othersaccharide species or other components. Such starting materials may beobtained conventionally, for example, by the partial hydrolysis ofstarch.

[0022] Suitable maltodextrins are sold under the trademark MALTRIN® byGrain Processing Corporation of Muscatine, Iowa. The MALTRIN®maltodextrins are mixtures of malto-oligosaccharides. Each MALTRIN®maltodextrin is characterized by a typical dextrose equivalent value(DE) and DP profile. Suitable MALTRIN maltodextrins that may beincorporated as borehole stability agents in accordance with theinvention, include, for example, MALTRIN® M040, MALTRIN® M050, MALTRIN®M100, MALTRIN® M150, and MALTRIN® M180. Typical approximate DP profilesfor the subject Maltrin maltodextrins are set forth in the followingtable (the DP profiles being approximate as indicated in the Table):Typical DP profile (% dry solids basis) DP profile M180 M150 M100 M050M040 DP > 8 46.6 ±4% 54.7   ±4% 67.8   ±4% 90.6 ±4% 88.5 ±4% DP 8 3.9±2% 4.8 ±1.5% 4.5 ±1.5% 1.5 ±1% 2.0 ±1% DP 7 9.5 ±2% 9.1 ±1.5% 7.0 ±1.5%1.5 ±1% 2.4 ±1% DP 6 11.4 ±2% 8.4 ±1.5% 6.1 ±1.5% 1.4 ±1% 1.8 ±1% DP 55.9 ±2% 4.7 ±1.5% 3.3 ±1.5% 1.3 ±1% 1.3 ±1% DP 4 6.4 ±2% 5.5 ±1.5% 3.7±1.5% 1.1 ±1% 1.4 ±1% DP 3 8.3 ±2% 6.7 ±1.5% 4.2 ±1.5% 1.0 ±1% 1.4 ±1%DP 2 6.2 ±2% 4.8   ±1% 2.5   ±1% 0.8* ±1% 0.9* ±1% DP 1 1.8 ±1.5%   1.3  ±1% 0.7*   ±1% 0.8* ±1% 0.3* ±1% DE** = 18 DE = 15 DE = 10 DE = 5 DE =5

[0023] Other suitable maltodextrins as may be known or discovered alsomay be considered useful in conjunction with the invention.

[0024] The maltodextrin may be present in any amount effective toinhibit shale swelling. When the drilling fluid includes a maltodextrinborehole stability agent and does not include hemicellulose, themaltodextrin preferably is present in a total amount ranging from about0.002 to about 0.2 lbs./gallon, more preferably about 0.01 to about 0.15lbs./gallon by dry basis weight of the maltodextrin. In this embodimentof the invention, these amounts are irrespective of the amount ofcellulose in the drilling fluid.

[0025] The borehole stability agent alternatively or additionally maycomprise a carboxyalkyl starch, preferably a carboxymethyl starch.Carboxymethyl starches are known in the art, and the preparation of suchstarches is described in Modified Starches: Properties and Uses(Wurzburg, O. B., Ed.) 1986 p. 187-88. When the drilling fluid includesa carboxymethyl starch but does not include any other borehole stabilityagent, the carboxymethyl starch preferably is present in the drillingfluid in an amount ranging from about 0.002 to about 0.2 lbs./gallon,more preferably about 0.01 to about 0.15 lbs./gallon. In thisembodiment, these amounts are irrespective of the amount of cellulose inthe composition. The carboxyalkyl starch may have a degree ofsubstitution (DS) of any suitable value. Adequate results may beobtained when the starch has a DS of about 0.2.

[0026] The drilling fluid of the invention may incorporate a boreholestability agent that includes a maltodextrin and hemicellulose in anycombination of two or more of the foregoing. In such case, the totalamount of the combined borehole stability agent present in the drillingfluid preferably ranges from about 0.002 to about 0.2 lbs./gallon by drybasis weight, irrespective of the amount of cellulose in the drillingfluid, with the maltodextrin, starch, and hemicellulose being present inany amount relative to one another. More generally, the boreholestability agent may be present in any amount effective to inhibit shaleswelling.

[0027] The drilling fluid further preferably includes a salt, preferablysodium or potassium chloride. Salts are believed to assist the alkylglycoside and/or the borehole stability agent in inhibiting shaleswelling. When sea water is used as the liquid base, or when the boreformation includes salt water, salt will be present in the form ofsodium chloride. Other salts that may be incorporated in the compositionof the invention include potassium chloride, calcium chloride, sodiumacetate, potassium acetate, calcium acetate, and the like. The salt ispreferably present in the drilling fluid in an amount ranging from about0.15 to about 0.8 lbs./gallon by dry basis weight but, more generally,may be present in any amount effective to assist in inhibiting shaleswelling.

[0028] The drilling fluid may include further additives as may beappropriate. Examples of additives that are known in the art includebarite, and other weighting agents, bentonite, low-and-medium-yieldclays, salt water clay, iron oxide, calcium carbonate, starch,carboxymethylcellulose, acrylonitrile, gums, molecularly dehydratedphosphate, tannin compound, quebracho, lignins, lignosulfate, mica,sugar cane fibers, and granular materials. Generally, the drilling fluidmay contain other ingredients such as weighting agents, viscosifiers,fluid loss reducing additives, Theological modifying additives,emulsifiers, seepage loss control additives, lubricity additives,defoamers, pH control additives, dispersants, and so forth, all of suchmaterials being solubilized, suspended or dispersed in the drillingfluid in such amounts as may be appropriate. It is generallycontemplated that any other suitable additive as is known or as may bediscovered may be employed in connection with the invention.

[0029] The invention further encompasses a drilling fluid additivecomposition that includes in one embodiment an alkyl glycoside and aborehole stability agent that is selected from among a maltodextrin, acarboxyalkyl starch, hemicellulose, and mixtures of the foregoing andthat includes in another embodiment desugared molasses solids inconjunction with one or more of the foregoing borehole stability agentsand/or in conjunction with an alkyl glycoside. In accordance with thisembodiment of the invention, the liquid base is not present, or ispresent in a smaller amount than is intended in the final drillingcomposition. The composition may be supplied to drillers, for example,to be used as an additive to seawater or brine in forming a drillingfluid in situ, or may be supplied to fabricators of drilling fluid to beblended with a liquid base. In accordance with this embodiment of theinvention, the hemicellulose, starch, and/or maltodextrin preferably arepresent in an amount ranging from about 0.1% to about 5% by the drybasis weight of the alkyl glucoside or desugared molasses solids (ortotal dry weight of the molasses solids and alkyl glucoside). Thecomposition may be dry or may be in liquid form, with the hemicellulose,starch, and maltodextrin being dissolved in a liquid. The composition ofthis embodiment of the invention may include other ingredients, such assalts or other additive, which other ingredient may be employed in suchamounts as may be desired.

[0030] The invention also encompasses a drilling fluid that includesmethyl glycoside or other alkyl glycoside and cellulose, the alkylglycoside being present in at least an amount effective to inhibit shaleswelling, and the cellulose being present in an amount of at least about0.1% by weight of the alkyl glycoside. It is contemplated that cellulosemay assist the alkyl glycoside in promoting borehole stability.Preferably, the cellulose is present in an amount of from about 0.1% toabout 5% by weight of the alkyl glycoside. In this embodiment of theinvention, the amount of cellulose in the drilling fluid is irrespectiveof the amount of dry hemicellulose or maltodextrin in the drillingfluid. In another embodiment, a drilling fluid comprises desugaredmolasses solids and cellulose, the cellulose being present in an amountranging from about 0.1% to about 5% by weight of the molasses solids.

[0031] The invention also encompasses a drilling apparatus. Withreference to the Figure, the apparatus is shown generally at 10 andincludes a drill string 11, the drill string 11 generally including adrive 12, a drill stem 14, and a drill bit 15 (the drive 12 is shown asa top drive, but other configurations, such as a rotary table, arepossible). The drill stem 14 may include components such as drillcollars, drill pipe and a kelly (not separately shown). The drill string11 is fluidically connected to a source 16 of drilling fluid whichcomprises the drilling fluid of one or more embodiments of theinvention.

[0032] Generally, the source 16 will be suction tanks 17 that arefluidically coupled to mud pumps 18 and optionally a mud pit (notshown). The mud pump circulates fluid through the drill string 11, i.e.,through and around the drill bit and/or through the annulus between thedrill stem and the borehole. The apparatus generally may take any otherconventional or otherwise suitable form and is not limited to theconfiguration shown in the Figure.

[0033] The invention also encompasses a process for drilling. Theprocess includes the step of circulating the drilling fluid of one ormore embodiments of the present invention through the drill string of adrilling apparatus during drilling operations. No special apparatus iscontemplated by the process of the invention, but instead the process iscontemplated to be useful in connection with any suitable drillingapparatus.

[0034] The following examples are provided to illustrate the presentinvention, but should not be construed as limiting in scope.

EXAMPLES

[0035] VOLCLAY clay bentonite tablets (American Colloid Company, Skokie,Ill.) were soaked in various drilling fluids and observed over a periodof time to simulate the effect of the drilling fluid on shale in a wellbore. The stability of each bentonite pellet was evaluated according tothe following scale:

[0036] 1=unaltered

[0037] 2=hard, intact but loose on surface

[0038] 3=swollen, softening, still intact

[0039] 4=together, but no integrity

[0040] 5=dissolved

[0041] These evaluations were designed to evaluate the drilling fluidsas against one another, rather than to directly evaluate efficiency inactual borehole conditions.

[0042] The drilling fluids were prepared using as alkyl glycosidesMeG-206 (a 60% aqueous solution of methyl glucoside existing as a 2:1ratio of α:β ratio isomers). MeG-365 (a 65% aqueous solution of methylglucoside existing as a 2:1 ratio of α:β isomers), and a 70% aqueoussolution of methyl glucoside existing as a 1:1 ratio of α:β ratio)(designated hereunder as MeG-207). As borehole stability agents,MALTRIN® M040, M100, and M180 (maltodextrins available from GrainProcessing Corporation of Muscatine, Iowa) and the soluble fractionresulting from alkaline treatment of corn hulls (designated hereunder as“HC”) were used. As a control, drilling fluids were prepared using onlywater and using only MeG-365 or MeG-207, without the addition ofhemicellulose, maltodextrin, or molasses. All of the drilling fluidswere prepared at an initial pH of 7 unless otherwise indicated.

Control Drilling fluids were prepared with MeG-365 and MeG-207. Thestability of the bentonite pellets in each fluid was evaluated. Thestability of the pellets in pure water also was evaluated. The followingresults were obtained.

[0043] Drilling Fluid 1 hr. 2 hr. 4 hr. 8 hr. 24 hr. H₂O 4 4.5 5 5 5 3652 2.5 3 4.5 5 207 1 1 1.5 2 3

[0044] Drilling Fluid 1 hr. 2 hr. 4 hr. 20 hr. 30 hr. 365 2 2 3.5 4.5 5207 1 1 1.5 2.5 3

[0045] Drilling Fluid 1 hr. 4 hr. 8 hr. 24 hr. 32 hr. 56 hr. 365 1.5 33.5 4.5 — — 207 1 1.5 2 3.5 4 5

[0046] Drilling Fluid 1 hr. 2 hr. 4 hr. 8 hr. 24 hr. 48 hr 365 1.5 2 33.5 4.5 — 207 1 1 1.5 1.5 3 —

[0047] The bentonite pellets were substantially unstable in water, andfared only somewhat better in the drilling fluids that included methylglucoside and water but that did not include maltodextrin,hemicellulose, or molasses.

Example 1 MeG+Maltodextrin

[0048] Drilling fluids were prepared using methyl glucoside andmaltodextrin, and the bentonite stability test was repeated for eachfluid. The following results were obtained. Maltodextrin percentages inthese tables express weight percent maltodextrin by dry basis of methylglucoside. Drilling Fluid 1 hr. 2 hr. 4 hr. 8 hr. 24 hr. 365 + 5% M040 11 1.5 1.5 2 365 + 5% M100 1 1 1.5 1.5 2.5 365 + 5% M180 1.5 1.5 2 2 4

[0049] Drilling Fluid 1 hr. 2 hr. 4 hr. 20 hr. 30 hr. 365 + 1% M040 1.52 2.5 4 4 365 + 3% M040 1 1.5 1.5 2.5 3

[0050] Drilling Fluid 1 hr. 4 hr. 8 hr. 24 hr. 365 + 0.5% M100 1.5 2 3.54 365 + 1% M100 1 1.5 1.5 3.5

[0051] As set forth above, the bentonite pellets generally were morestable in the drilling fluids of Example 1 than in the control drillingfluids.

Example 2 MeG+Maltodextrin+NaCl

[0052] Drilling fluids were prepared using MeG, maltrodextrin, andsodium chloride. The bentonite stability test was repeated for eachfluid, and the following results were obtained. Sodium chloridepercentages in these tables express weight percent sodium chloride bydry basis weight of methyl glucoside. Drilling Fluid 1 hr. 2 hr. 4 hr. 8hr. 24 hr. 365 + 5% M040 + 10% NaCl 1 1 1 1.5 2 365 + 5% M100 + 10% NaCl1 1 1.5 1.5 2 365 + 5% M180 + 10% NaCl 1 1.5 1.5 2 4

[0053] Drilling Fluid 1 hr. 2 hr. 4 hr. 20 hr. 30 hr. 365 + 1% M040 + 5%NaCl 1.5 1.5 1.5 2 3 365 + 3% M100 + 5% NaCl 1 1 1.5 2 3

[0054] Drilling Fluid 1 hr. 4 hr. 8 hr. 24 hr. 365 + 0.5% M040 + 2% NaCl1.5 1.5 2.5 3.5 365 + 1% M100 + 2% NaCl 1 1.5 1.5 3 365 + 0.5% M100 + 5%NaCl 1.5 2 2 3.5 365 + 1% M100 + 5% NaCl 1 1.5 1.5 3.5

[0055] As seen, the addition of sodium chloride to the drilling fluidrendered the fluid retention less aggressive toward the bentonitepellets.

Example 3 MeG+HC

[0056] Drilling fluids were prepared using MeG and the hemicellulosefraction of alkaline treated corn hulls. The bentonite stability testswere repeated, and the following examples were obtained. Hemicellulosepercentages in these tables are expressed as weight percent dryhemicellulose provided in the HC solution by dry basis MeG. DrillingFluid 1 hr. 2 hr. 4 hr. 8 hr. 365 + 0.6% hemicellulose 1 1 1 1.5 365 +0.6% hemicellulose 2.5 3.5 4 4.5 (solution diluted to 50%)

[0057] Drilling Fluid 1 hr. 2 hr. 4 hr. 20 hr. 30 hr. 365 + 1%hemicellulose 1 1 1 2 2.5

[0058] Drilling Fluid 1 hr. 2 hr. 4 hr. 8 hr. 24 hr. 48 hr. 207 + 0.5%hemicellulose 1 1 1 1 1.5 1.5 365 + 0.6% hemicellulose 1 1 1 1.5 — —

[0059] As seen, the bentonite pellets were substantially more stable inthe drilling fluids prepared using MeG and hemicellulose than in thedrilling fluids prepared using only MeG.

Example 4 MeG+HC+NaCl

[0060] Drilling fluids were prepared using MeG, the hemicellulose andsodium chloride. The bentonite stability tests were repeated and thefollowing results were obtained. Drilling Fluid 1 hr. 2 hr. 4 hr. 20 hr.30 hr. 365 + 1% hemicellulose + 5% NaCl 1 1 1 1.5 2

[0061] Drilling Fluid 1 hr. 4 hr. 8 hr. 24 hr. 32 hr. 56 hr. 365 + 0.5%hemicellulose + 1 1.5 2 2 2.5 3 2% NaCl 365 + 1% hemicellulose + 1 1 1.51.5 2 2.5 5% NaCl

[0062] As seen, the bentonite pellets were substantially more stable inthe drilling fluids thus prepared then in the control drilling fluids.Addition of salt to the drilling fluid reduced the aggressiveness of thefluid towards the bentonite pellets.

Comparative Examples 1-11

[0063] Drilling fluids were prepared using MeG and other organicadditives in accordance with the following table. The bentonitestability test was repeated for each drilling fluid, giving thefollowing results: Drilling Fluid 1 hr. 2 hr. 4 hr. 8 hr. 24 hr. 365 +10% NaCl* 2 2.5 3.5 4 5 365 at pH 10 2.5 3 3.5 4 5 365 + 5%hydroxy-propyl starch* 2 2.5 3 3 — 365 + 2% corn starch* 2 2.5 2.5 4 —365 + 2% solubilized starch* 1.5 2 2.5 3.5 4.5 365 + 2% polyethyleneoxide* 2 2.5 3.5 4 4.5 365 + 2% ethoxylated starch* 1.5 2.5 3.5 4 4.5365 + 2% acid modified starch* 1.5 2 3 4 4.5 365 + 2% cationic starch*1.5 2 3.5 4 4.5 365 + 2% gum arabic* 1.5 2 3 4.5 — 365 + 2% guar gum* 11 1.5 2 —

[0064] As seen, the bentonite pellets generally were not as stable inthe drilling fluids of the comparative examples as in the drillingfluids of the invention. These results demonstrate the surprisingbenefits of using maltodextrin and/or hemicellulose as a boreholestability agent as compared with other organic species.

Example 5 Water Activity

[0065] The water activity, or relative humidity that exists in the spaceabove the drilling fluid in an enclosed container, was evaluated foreach of the drilling fluids of the invention and for control drillingfluids. It is believed that the stability of wellbore formations in adrilling fluid generally improves as the water activity value of thedrilling fluids decreases.

[0066] The following results were obtained: Drilling Fluid Wateractivity @ 25° C. (Control) Pure H₂O 1.01 (as measured) MeG-365 0.864MeG-207 0.789 MeG-207 diluted to 65% solids 0.851 (Invention) MeG-207 +0.5% hemicellulose⁽¹⁾ 0.780 MeG-365 + 0.5% hemicellulose⁽¹⁾ 0.889MeG-365 + 1% hemicellulose⁽¹⁾ 0.836 MeG-365 + 2% hemicellulose⁽¹⁾ 0.816MeG-365 + 0.5% hemicellulose⁽¹⁾ + 2% NaCl⁽²⁾ 0.810 MeG-365 + 0.5%hemicellulose⁽¹⁾ + 5% NaCl⁽²⁾ 0.727 MeG-365 + 1% hemicellulose⁽¹⁾ + 5%NaCl⁽²⁾ 0.768 MeG-365 + 0.5% Maltodextrin⁽²⁾ 0.844 MeG-365 + 1%Maltodextrin⁽²⁾ 0.855 MeG-365 + 2% Maltodextrin⁽²⁾ 0.845 MeG-365 + 0.5%Maltodextrin⁽²⁾ + 2% NaCl⁽²⁾ 0.820 MeG-365 + 0.5% Maltodextrin⁽²⁾ + 5%NaCl⁽²⁾ 0.759 MeG-365 + 1% Maltodextrin⁽²⁾ + 2% NaCl⁽²⁾ 0.811 MeG-365 +1% Maltodextrin⁽²⁾ + 5% NaC⁽²⁾l 0.756

Example 6

[0067] A drilling fluid comprising MeG-365, 5% MALTRIN® M040 (on drybasis MeG), and 0.6% hemicellulose (on dry basis hemicellulose) isprepared.

Example 7

[0068] A drilling composition comprising 50% polyglycerine, 20% water,1% hemicellulose (dry basis), and 29% MeG (2:1 α:β)(dry basis) isprepared. The MeG is obtained from MeG-365.

Example 8

[0069] A drilling composition comprising 50% polyglycerine, 20% water,1% maltodextrin (MALTRIN® M180) (dry basis), and 29% MeG (2:1 α:β)(drybasis) is prepared. The MeG is obtained from MeG-360.

Example 9

[0070] A composition comprising 65% MeG and 2.5% hemicellulose isprepared (balance water). The composition is suitable for addition toseawater to form a drilling fluid.

Example 10

[0071] A drilling fluid comprising the following ingredients isprepared: 350 lbs. Fresh Water 20 lbs. Bentonite 4 lbs. Lime 3 lbs.Polysaccharide deflocculant 0.75 lb. KOH 1-2 lbs. Drilling Starch 0.25lb. Lignite 10-30 lbs. MeG (2:1 α:β) 0.1-0.3 lbs. Hemicellulose

Example 11

[0072] A composition comprising the following ingredients is prepared:350 lbs. Fresh Water 20 lbs. Bentonite 4 lbs. Lime 3 lbs. PolysaccharideDeflocculant 0.75 lb. KOH 1-2 lbs. Drilling Starch 0.25 lb. Lignite10-30 lbs. MeG (2:1 α:β) 0.1-0.3 lbs. Maltodextrin (MALTRIN ® M040)

Example 12

[0073] A composition comprising the following ingredients is prepared:250 lbs. Sea Water 11 lbs. KCl 100 lbs. Bentonite 0.50 lb. NaOH 1-4 lbs.Drilling Starch 10-30 lbs. MeG(2:1 α:β) 0.1-0.3 lbs. Hemicellulose

Example 13

[0074] A composition comprising the following ingredients is prepared:250 lbs. Sea Water 11 lbs. KCl 100 lbs. Bentonite 0.50 lb. NaOH 1-4 lbs.Drilling Starch 10-30 lbs. MeG (2:1 α:β) 0.1-0.3 lbs. Maltodextrin

Example 14

[0075] Corn hulls from a corn wet milling operation are wet screenedthrough a U.S. No. 6 screen at about 50° C. using sufficient water tosubstantially remove the fine fiber, most of the starch and some of theprotein and lipid material present. The hulls remaining on the screenare then slurried in water and the pH of the slurry is adjusted withlime to pH 6.5 and treated at 79° C. for 1 hour with a B. subtilisalpha-amylase (obtained from Genencor International) at a dosage ofabout 3 liquefons/g (units as defined by Genencor) of hull solids. Thehulls are filtered, washed and dried to a moisture range of 5 to 10percent in a forced air oven at 70° C.

[0076] Fifty-two grams (50.6 g d.b.) of the hulls are slurried in 1000ml of 69 percent aqueous ethanol (v/v) containing 5 g of reagent gradeNaOH, and the slurry is heated in a Parr model 4522 pressure reactor at100° C. for 3 hours. The reaction mixture, at a temperature of about 50°C., is then filtered through a Buchner funnel using Whatman No. 3 filterpaper.

[0077] The filter cake is then extracted by refluxing at about 82° C.with 1000 ml of 69 percent aqueous ethanol (v/v) for one hour, and themixture is filtered at a temperature of about 50° C. through a Buchnerfunnel using Whatman No. 3 paper. The filter cake is next slurried in1000 ml of 69 percent aqueous ethanol (v/v), and the slurry is adjustedwith diluted HCl to pH 2 and is filtered as above. The filtrate is nextcombined with the filtrates from the two previous filtrations. Thecombined filtrates then are adjusted to pH 2 with HCl, and evaporated todryness. The residue is dried in a vacuum oven at 70° C.

[0078] To extract the hemicellulose, the filter cake from the aboveprocedure is slurried in 1000 ml of deionized water, held at roomtemperature for about two hours, and filtered through a coarse sinteredglass funnel. This procedure is repeated a second time. The filtratesfrom these two extractions are combined and concentrated to about 10percent solids by evaporation of the water on a vacuum rotary evaporatorat a temperature of 40° C. and a vacuum of about 20 inches of mercury.The concentrated hemicellulose solution is then dried on a drum drierhaving a surface temperature of 130° C., and the dried hemicellulose isground in a Waring blender.

[0079] The hemicellulose is added to 10 kg MeG-365 in an amount of 2.5%hemicellulose (on dry basis MeG) to form a drilling fluid.

Example 15

[0080] Various drilling fluids were prepared as set forth in detailbelow. The ability of each fluid to stabilize shale was evaluated bymeasuring the amount of time required for a bentonite clay pellet tobreak down (as was determined when the pellet had reached or passed “4”on the scale discussed in the earlier Examples). For control purposes,drilling fluids that included methyl glycoside but that did not includea borehole stability agent were evaluated. The compositions of thedrilling fluids that were prepared and the results of the stabilitytests are set forth below. Drilling Fluid Time to pellet breakdown 365<1 day 207 <2 days

[0081] Drilling Fluid Time to pellet breakdown 365 + 4% M040 + 4% KOH 7days 365 + 4% CMS + 4% KOH >25 days 365 + 2% CMS + 4% KOH 5 days 365 +1% CMS + 4% KOH 4 days 365 + 2% CMS + 2% KOH 4 days 365 + 1% CMS + 2%KOH 3 days

[0082] CMS is carboxymethyl starch having a DS of 0.2

[0083] It is thus seen that both the maltodextrin and the carboxymethylstarch tested functioned as borehole stability agents.

[0084] As a control for Examples 16 through 20, the following drillingfluids were evaluated. Drilling Fluid 4 hr. 8 hr. 16 hr. MeG-206 3 3.5 4MeG-207 1.5 2 2

Example 16

[0085] Five hundred g dry basis corn hulls containing 766 g water wasadded to sufficient water to give a total weight of 5000 g. The stirredslurry was heated and maintained at 82° C. to 96° C. for two hours. Thehot slurry was then filtered through a No. 60 Mesh A.S.T.M.E. StandardTesting Sieve. The retained solids were subjected to a second treatmentof slurrying, stewing, and filtering, and then to a third treatment ofslurrying, stewing, and filtering. The retained solids were crumbled,placed on screens, and allowed to air-dry at room temperature.

[0086] One hundred g dry basis of the treated corn hulls thus obtainedwere added to a solution already containing 1610 mL 190 proof ethanol,390 mL water, and 20 g 50% NaOH in a reaction flask equipped with areflux condenser and mechanical stirring. The stirred reaction mixturewas heated to the reflux temperature and then refluxed for three hoursat the reflux temperature of 78° C. The reaction mixture was cooled to40° C., and then it was vacuum filtered across a 40-60° C. fritted glassfunnel. The retained solids were returned to the reaction flask andreslurried in a solution already containing 1610 mL 190 proof ethanoland 390 mL water. The slurry was heated to reflux temperature and thenrefluxed for one hour at the reflux temperature of 78° C. The reactionmixture was cooled to 20° C., and then it was vacuum filtered across a40-60° C. fritted glass funnel. The retained solids were reslurried in asolution already containing 1610 mL 190 proof ethanol and 390 mL waterat 20° C., and then the pH of the slurry was adjusted to 6.5 with 5.8Nhydrochloric acid. The slurry was then vacuum filtered across a 40-60°C. fritted glass funnel.

[0087] The retained solids were reslurried in 2000 mL water in areaction flask equipped with a reflux condenser and mechanical stirring.The stirred mixture was heated to the reflux temperature and thenrefluxed for two hours at the reflux temperature of 98° C. The mixturewas cooled to 50° C., and then was vacuum filtered across a 40-60° C.fritted glass funnel. The filtrate, referred to as FILTRATE A, whichcontained corn hull hemicellulose, was retained. The retained solidswere reslurried in 2000 mL water in a reaction flask equipped with areflux condenser and mechanical stirring. The stirred mixture was heatedto the reflux temperature and then refluxed for two hours at the refluxtemperature of 98° C.

[0088] The mixture was cooled to 50° C., and then it was vacuum filteredacross a 40-60° C. fritted glass funnel. The filtrate, referred to asFILTRATE B, containing the corn hull hemicellulose, was retained. Theretained solids were reslurried in 2000 mL water in a reaction flaskequipped with a reflux condenser and mechanical stirring. The stirredmixture was heated to the reflux temperature and then refluxed for twohours at the reflux temperature of 98° C. The mixture was cooled to 50°C., and then it was vacuum filtered across a 40-60° C. fritted glassfunnel. The filtrate, referred to as FILTRATE C, containing the cornhull hemicellulose was retained. The combined FILTRATES A, B, and Ccontaining the corn hull hemicellulose were assayed to contain 54.5 gsolids. Combined filtrates A, B, and C then were spray dried. Theresulting hemicellulose was formulated into an adhesive paste by mixing15 parts weight hemicellulose of the spray-dried hemicellulose with 85parts water.

[0089] A drilling fluid comprising 48.5% MeG-206 (60% solids), 46.5%desugared sugar beet molasses, and 3% hemicellulose was prepared asdescribed above and evaluated for bentonite pellet stability. Thefollowing results were obtained. 4 hr. 8 hr. 16 hr. 1.5 2 2

[0090] As seen, this product established satisfactory results.

Example 17

[0091] A drilling fluid composed of 48% MeG-206 (60% solids), 48%desugared sugar beet molasses (60% solids) and 4% corn hullhemicellulose prepared as in Example 16 was prepared and evaluated forbentonite pellet stability. The following results were obtained. 4 hr. 8hr. 16 hr. 2 1.5 1.5

[0092] As seen, this product exhibited excellent results.

Example 18

[0093] A drilling fluid composed of 97% MeG-206 and 3% corn hullhemicellulose prepared as in Example 16 was prepared and evaluated forbentonite pellet stability. The following results were obtained. 4 hr. 8hr. 16 hr. 2 3 3.5

[0094] As seen, this product exhibited somewhat satisfactory results.

Example 19

[0095] A drilling fluid comprising 50% MeG-206 and 50% desugared sugarbeet molasses was prepared and evaluated for bentonite pellet stability.The following results were obtained. 4 hr. 8 hr. 16 hr. 1.5 2.5 2.5

[0096] As seen, this product exhibited satisfactory results.

Example 20

[0097] A drilling fluid comprising 49% MeG-206, 49% desugared sugar beetmolasses, and 2% corn hull hemicellulose prepared in accordance with theteachings of U.S. Pat. No. 6,063,178 to McPherson et al., assignor toGrain Processing Corporation of Muscatine, Iowa was prepared andevaluated for bentonite pellet stability. The following results wereobtained. 4 hr. 8 hr. 16 hr. 1 1.5 1.5

[0098] As seen, this product exhibited excellent results.

Example 21

[0099] The following drilling fluids were evaluated for bentonite pelletstability at 16 hours. The results are shown following the descriptionof the drilling fluid. In this example, the hemicellulose was a drysolid prepared in accordance with the description provided in prior U.S.Pat. No. 6,063,178. Drilling Fluid 16 hr. MeG-206 4 Desugared Sugar BeetMolasses (60% solids) 2.5 98% MeG-206 + 2% hemicellulose 3 98% DesugaredSugar Beet Molasses (60% solids) + 2 2% hemicellulose

Example 22

[0100] A drilling fluid comprising desugared cane sugar molasses thathas been diluted to 30% solids with salt water is circulated through adrill string.

[0101] Thus, the foregoing general objects have been satisfied. Theinvention provides a drilling fluid that is suitable for use inconnection with borehole drilling. The invention further provides adrilling apparatus and method that incorporate the improved drillingfluid.

[0102] While particular embodiments of the invention have been shown, itwill be understood that the invention is not limited thereto sincemodifications may be made by those skilled in the art, particularly inlight of the foregoing teachings. For instance, the pH or salt contentof the disclosed fluids may be modified, or, more generally, othercomponents may be altered. It is therefore contemplated that theinvention encompasses the subject matter of the following claims andequivalents thereof. All references cited herein are hereby incorporatedby reference in their entireties.

What is claimed is:
 1. A drilling fluid comprising: a liquid baseselected from the group consisting of water, water-miscible liquids, andmixtures thereof; an alkyl glycoside, said alkyl glycoside being presentin at least an amount effective to inhibit shale swelling and beingselected from among the α-form, the β-form, and mixtures thereof, saidalkyl glycoside selected from among the methyl, ethyl, propyl, and butylglycosides of glucose, maltose, maltotriose, and maltotetraose; and aborehole stability agent selected from the group consisting of amaltodextrin, a carboxyalkyl starch, hemicellulose, and mixturesthereof, said borehole stability agent being present in at least anamount effective to inhibit shale swelling.
 2. A composition accordingto claim 1, wherein said liquid base comprises water.
 3. A compositionaccording to claim 1, wherein said liquid base includes polyglycerine.4. A composition according to claim 3, wherein said liquid base includespolyglycerine and water.
 5. A composition according to claim 1, saidalkyl glycoside comprising methyl glucoside.
 6. A composition accordingto claim 1, said alkyl glycoside being present in an amount ranging fromabout 2 to about 4 lbs./gallon by dry basis weight.
 7. A compositionaccording to claim 6, said methyl glucoside being present in the amountof about 3 lbs./gallon by dry basis weight and comprising a 2:1 α:βmixture of methyl glucoside.
 8. A composition according to claim 6, saidmethyl glucoside being present in the amount of about 3 lbs./gallon bydry basis weight and comprising a 1:1 α:β mixture of methyl glucoside.9. A composition according to claim 1, said borehole stability agentcomprising hemicellulose.
 10. A composition according to claim 9,wherein hemicellulose is present in said drilling fluid in an amountranging from about 0.002 to about 0.2 lbs./gallon by dry basis weight.11. A composition according to claim 9, wherein said hemicellulosecomprises a hemicellulose fraction obtained via alkaline hydrolysis ofcorn hulls.
 12. A composition according to claim 1, said boreholestability agent comprising a maltodextrin.
 13. A composition accordingto claim 12, wherein said maltodextrin is present in an amount rangingfrom about 0.002 to about 0.2 lbs./gallon by dry basis weight.
 14. Acomposition according to claim 1, said borehole stability agentcomprising a mixture of maltodextrin and hemicellulose.
 15. Acomposition according to claim 14, wherein said borehole stability agentis present in a total amount ranging from about 0.002 to about 0.2lbs./gallon by dry basis weight.
 16. A composition according to claim 1,said borehole stability agent comprising a carboxymethyl starch.
 17. Acomposition according to claim 16, said carboxymethyl starch having a DSof about 0.2.
 18. A composition according to claim 16, said boreholestability agent comprising a mixture of carboxymethyl starch andmaltodextrin.
 19. A composition according to claim 16, said boreholestability agent comprising a mixture of carboxymethyl starch andhemicellulose
 20. A drilling apparatus comprising: a drill string; atleast one pump for circulating a drilling fluid through at least aportion of said drill string, said pump being fluidically connected to asource of drilling fluid, said drilling fluid comprising: a liquid baseselected from the group consisting of water, water-miscible liquids, andmixtures thereof; an alkyl glycoside, said alkyl glycoside being presentin at least an amount effective to inhibit shale swelling and beingselected from among the α-form, the β-form, and mixtures thereof, saidalkyl glycoside selected from among the methyl, ethyl, propyl, and butylglycosides; and a borehole stability agent selected from the groupconsisting of a maltodextrin, a carboxyalkyl starch, hemicellulose, andmixtures thereof, said borehole stability agent being present in atleast an amount effective to inhibit shale swelling.
 21. A drillingprocess comprising the steps of: cutting a borehole into the earth usinga drill string; and circulating a drilling fluid through at least aportion of said drill string, said drilling fluid comprising: a liquidbase selected from the group consisting of water, water-miscibleliquids, and mixtures thereof; an alkyl glycoside, said alkyl glucosidebeing present in at least an amount effective to inhibit shale swellingand being selected from among the α-form, the β-form, and mixturesthereof, said alkyl glycoside selected from among the methyl, ethyl,propyl, and butyl glycosides of glucose, maltose, maltotriose andmaltotetraose; and a borehole stability agent selected from the groupconsisting of a maltodextrin, a carboxyalkyl starch, hemicellulose, andmixtures thereof, said borehole stability agent being present in atleast an amount effective to inhibit shale swelling.
 22. A compositioncomprising: an alkyl glycoside selected from among the α-form, theβ-form, and mixtures thereof, said alkyl glycoside selected from amongthe methyl, ethyl, propyl, and butyl glucosides of glucose, maltose,maltotriose, and maltotetraose; and a borehole stability agent, saidborehole stability agent being selected from the group consisting of amaltodextrin, a carboxyalkyl starch, hemicellulose, and mixturesthereof, said borehole stability agent being present in an amountranging from about 0.1% to about 5% by dry basis weight of said alkylglucoside.
 23. A drilling fluid comprising: a liquid base selected fromthe group consisting of water, water-miscible liquids, and mixturesthereof; an alkyl glycoside, said alkyl glycoside being present in atleast an amount effective to inhibit shale swelling and being selectedfrom among the α-form, the β-form, and mixtures thereof, said alkylglycoside selected from among the methyl, ethyl, propyl, and butylglycosides of glucose, maltose, maltotriose, and maltotetraose; andcellulose, said cellulose being present in an amount of at least 0.1% byweight of said alkyl glycoside.
 24. A drilling fluid according to claim23, wherein said cellulose is present in an amount ranging from about0.1% to about 5% by weight of said alkyl glycoside.
 25. A drilling fluidcomprising: a liquid base selected from the group consisting of water,water-miscible liquids, and mixtures thereof; desugared molasses solids,said desugared molasses solids being present in at least an amounteffective to inhibit shale swelling; and a borehole stability agentselected from the group consisting of a maltodextrin, a carboxyalkylstarch, hemicellulose, and mixtures thereof, said borehole stabilityagent being present in at least an amount effective to inhibit shaleswelling.
 26. A composition according to claim 25, wherein said liquidbase comprises water.
 27. A composition according to claim 25, whereinsaid liquid base includes polyglycerine.
 28. A composition according toclaim 25, wherein said liquid base includes polyglycerine and water. 29.A composition according to claim 25, said borehole stability agentcomprising hemicellulose.
 30. A composition according to claim 29,wherein hemicellulose is present in said drilling fluid in an amountranging from about 0.002 to about 0.2 lbs./gallon by dry basis weight.31. A composition according to claim 29, wherein said hemicellulosecomprises a hemicellulose fraction obtained via alkaline hydrolysis ofcorn hulls.
 32. A composition according to claim 25, said boreholestability agent comprising a maltodextrin.
 33. A composition accordingto claim 32, wherein said maltodextrin is present in an amount rangingfrom about 0.002 to about 0.2 lbs./gallon by dry basis weight.
 34. Acomposition according to claim 25, said borehole stability agentcomprising a mixture of maltodextrin and hemicellulose.
 35. Acomposition according to claim 34, wherein said borehole stability agentis present in a total amount ranging from about 0.002 to about 0.2lbs./gallon by dry basis weight.
 36. A composition according to claim25, said borehole stability agent comprising a carboxyalkyl starch. 37.A composition according to claim 36, said carboxyalkyl starch having aDS of about 0.2.
 38. A drilling fluid comprising: a liquid base selectedfrom the group consisting of water, water-miscible liquids, and mixturesthereof; desugared molasses solids; and an alkyl glucoside, the alkylglucoside being selected from among the α-form, the β-form, and mixturesthereof and being selected from among the methyl, ethyl, propyl, andbetyl glucosides of glucose, maltose, maltotriose, and maltotetraose,the desugared molasses solids and alkyl glucoside being present in atleast a total amount effective to inhibit shale swelling.
 39. A drillingfluid according to claim 38, further including a borehole stabilityagent selected from the group consisting of a carboxyalkyl starch,hemicellulose, and a maltodextrin, said borehole stability agent beingpresent in at least an amount effective to inhibit shale swelling.
 40. Adrilling apparatus comprising: a drill string; at least one pump forcirculating a drilling fluid through at least a portion of said drillstring, said pump being fluidically connected to a source of drillingfluid, said drilling fluid comprising: a liquid base selected from thegroup consisting of water, water-miscible liquids, and mixtures thereof,and desugared molasses solids, said desugared molasses solids beingpresent in at least an amount effective to inhibit shale swelling.
 41. Adrilling apparatus according to claim 40, said drilling fluid furtherincluding a borehole stability agent selected from the group consistingof a carboxyalkyl starch, a maltodextrin, hemicellulose, and mixturesthereof, said borehole stability agent being present in at least anamount effective to inhibit shale swelling.
 42. A drilling apparatusaccording to claim 40, said drilling fluid further including an alkylglycoside, said alkyl glycoside being present in at least an amounteffective to inhibit shale swelling and being selected from among theα-form, the β-form, and mixtures thereof, said alkyl glycoside selectedfrom among the methyl, ethyl, propyl, and butyl glucosides of glucose,maltose, maltotriose, and maltotetraose.
 43. A drilling apparatusaccording to claim 42, said drilling fluid further including a boreholestability agent selected from the group consisting of a carboxyalkylstarch, a maltodextrin, hemicellulose, and mixtures thereof, saidborehole stability agent being present in at least an amount effectiveto inhibit shale swelling.
 44. A drilling process comprising the stepsof: cutting a borehole into the earth using a drill string; andcirculating a drilling fluid through at least a portion of said drillstring, said drilling fluid comprising: a liquid base selected from thegroup consisting of water, water-miscible liquids, and mixtures thereof;and desugared molasses solids, said desugared molasses solids beingpresent in at least an amount effective to inhibit shale swelling.
 45. Adrilling process according to claim 44, said drilling fluid furtherincluding a borehole stability agent selected from the group consistingof a carboxyalkyl starch, a maltodextrin, hemicellulose, and mixturesthereof, said borehole stability agent being present in at least anamount effective to inhibit shale swelling.
 46. A drilling processaccording to claim 44, said drilling fluid further including an alkylglycoside, said alkyl glycoside being present in at least an amounteffective to inhibit shale swelling and being selected from among theα-form, the β-form, and mixtures thereof, said alkyl glycoside selectedfrom among the methyl, ethyl, propyl, and butyl glucosides of glucose,maltose, maltotriose, and maltotetraose.
 47. A drilling processaccording to claim 46, said drilling fluid further including a boreholestability agent selected from the group consisting of a carboxyalkylstarch, a maltodextrin, hemicellulose, and mixtures thereof, saidborehole stability agent being present in at least an amount effectiveto inhibit shale swelling.
 48. A composition comprising: an alkylglycoside selected from among the α-form, the β-form, and mixturesthereof, said alkyl glycoside selected from among the methyl, ethyl,propyl, and butyl glucosides of glucose, maltose, maltotriose, andmaltotetraose; and desugared molasses solids, said desugared molassessolids being present in at least an amount effective to inhibit shaleswelling.
 49. A composition according to claim 48, further comprising aborehole stability agent, said borehole stability agent being selectedfrom the group consisting of a carboxyalkyl starch, a maltodextrin,hemicellulose, and mixtures thereof, said borehole stability agent beingpresent in an amount ranging from about 0.1% to about 15% by dry basisweight of said alkyl glucoside.